The Pinakothek der Moderne in Munich said the 51-year-old technical employee smuggled the 60cm x 120cm painting into the building and installed it on an empty wall.

As well as being fired, he is now being investigated by police for property damage after drilling two holes in the wall to hang the artwork, the Süddeutsche Zeitung reports.

The man describes himself as a freelance artist and reportedly told police that he hoped his guerilla installation would lead to a career breakthrough.

The museum has not disclosed what the artwork depicted.